So, for instance facebook's search bar has faint word that says "search", but when you click on the bar, it becomes blank and you may begin typing, when you click away the "search" goes back.

Similarly, SO's ask a question title box has faint words that go away when you start typing.

I'm not too sure what this effect is called, but I'm wondering if theres a jQuery plugin that helps to achieve this. This isn't particularly difficult to program, but I thought why reinvent the wheel if someone already made a plugin for it.